From 2db3df902789483a8ea8ee4e250409b116ccdf36 Mon Sep 17 00:00:00 2001
From: Jakob Bornecrantz <jakob@collabora.com>
Date: Thu, 5 Sep 2019 23:15:25 +0100
Subject: [PATCH] st/oxr: Add oxr_sink_logger, the slog-inator!

---
 src/xrt/state_trackers/oxr/oxr_logger.cpp | 76 ++++++++++++++++++++++-
 src/xrt/state_trackers/oxr/oxr_logger.h   | 51 +++++++++++++++
 2 files changed, 126 insertions(+), 1 deletion(-)

diff --git a/src/xrt/state_trackers/oxr/oxr_logger.cpp b/src/xrt/state_trackers/oxr/oxr_logger.cpp
index 25d8c647e..b0d9b11fd 100644
--- a/src/xrt/state_trackers/oxr/oxr_logger.cpp
+++ b/src/xrt/state_trackers/oxr/oxr_logger.cpp
@@ -11,6 +11,7 @@
 #include <stdarg.h>
 
 #include "xrt/xrt_compiler.h"
+#include "util/u_misc.h"
 #include "util/u_debug.h"
 
 #include "oxr_objects.h"
@@ -25,7 +26,6 @@ DEBUG_GET_ONCE_BOOL_OPTION(break_on_error, "OXR_BREAK_ON_ERROR", false)
 static const char *
 oxr_result_to_string(XrResult result);
 
-
 void
 oxr_log_init(struct oxr_logger *logger, const char *api_func_name)
 {
@@ -119,3 +119,77 @@ oxr_result_to_string(XrResult result)
 	}
 	// clang-format on
 }
+
+
+/*
+ *
+ * Sink logger.
+ *
+ */
+
+static void
+oxr_slog_ensure(struct oxr_sink_logger *slog, size_t extra)
+{
+	while (slog->store_size < extra + slog->length) {
+		slog->store_size += 1024;
+	}
+
+	slog->store = (char *)realloc(slog->store, slog->store_size);
+}
+
+extern "C" void
+oxr_slog(struct oxr_sink_logger *slog, const char *fmt, ...)
+{
+	va_list args;
+
+	int ret = 0;
+
+	va_start(args, fmt);
+	ret = vsnprintf(NULL, 0, fmt, args);
+	va_end(args);
+
+	if (ret <= 0) {
+		return;
+	}
+
+	oxr_slog_ensure(slog, ret + 1);
+
+	va_start(args, fmt);
+	ret = vsnprintf(slog->store + slog->length,
+	                slog->store_size - slog->length, fmt, args);
+	va_end(args);
+
+	slog->length += ret;
+}
+
+extern "C" void
+oxr_slog_free(struct oxr_sink_logger *slog)
+{
+	free(slog->store);
+	slog->length = 0;
+	slog->store_size = 0;
+}
+
+extern "C" void
+oxr_log_slog(struct oxr_logger *log, struct oxr_sink_logger *slog)
+{
+	oxr_log(log, "%s", slog->store);
+	oxr_slog_free(slog);
+}
+
+extern "C" void
+oxr_warn_slog(struct oxr_logger *log, struct oxr_sink_logger *slog)
+{
+	oxr_warn(log, "%s", slog->store);
+	oxr_slog_free(slog);
+}
+
+extern "C" XrResult
+oxr_error_slog(struct oxr_logger *log,
+               XrResult res,
+               struct oxr_sink_logger *slog)
+{
+	oxr_error(log, res, "%s", slog->store);
+	oxr_slog_free(slog);
+	return res;
+}
diff --git a/src/xrt/state_trackers/oxr/oxr_logger.h b/src/xrt/state_trackers/oxr/oxr_logger.h
index 4e768a0df..5d2d4a3d5 100644
--- a/src/xrt/state_trackers/oxr/oxr_logger.h
+++ b/src/xrt/state_trackers/oxr/oxr_logger.h
@@ -73,6 +73,57 @@ XrResult
 oxr_error(struct oxr_logger *logger, XrResult result, const char *fmt, ...)
     XRT_PRINTF_FORMAT(3, 4);
 
+
+
+/*
+ *
+ * Sink logger.
+ *
+ */
+
+/*!
+ * Allocate on the stack, make sure to zero initialize.
+ */
+struct oxr_sink_logger
+{
+	char *store;
+	size_t store_size;
+	size_t length;
+};
+
+/*!
+ * Log string to sink logger.
+ */
+void
+oxr_slog(struct oxr_sink_logger *slog, const char *fmt, ...);
+
+/*!
+ * Abort logging, frees all internal data.
+ */
+void
+oxr_slog_abort(struct oxr_sink_logger *slog);
+
+/*!
+ * Flush sink as a log message, frees all internal data.
+ */
+void
+oxr_log_slog(struct oxr_logger *log, struct oxr_sink_logger *slog);
+
+/*!
+ * Flush sink as a warning message, frees all internal data.
+ */
+void
+oxr_warn_slog(struct oxr_logger *log, struct oxr_sink_logger *slog);
+
+/*!
+ * Flush sink as a error message, frees all internal data.
+ */
+XrResult
+oxr_error_slog(struct oxr_logger *log,
+               XrResult res,
+               struct oxr_sink_logger *slog);
+
+
 /*!
  * @}
  */